The bill, proposed by Mykola Rudkovskyi of the ruling Regions Party, would allow prisoners to appeal for permission to go aboard for medical treatment not available in Ukraine, RIA Novosti reported.
Once treatment is completed, the prisoners would return to Ukraine to complete their sentences.
Ukrainian President Viktor Yanukovych said he would sign such a bill if it is approved by parliament.
The move may smooth over relations between Ukraine and the European Union, which has urged Kiev to pardon Tymoshenko.
Tymoshenko, who has been suffering from back pains, is serving a seven-year sentence for a 2009 gas deal with Russia. Tymoshenko's supporters say her prosecution was politically motivated.